1. Field of the Invention
The present invention relates to a wire grid polarizer composed of an inorganic material, a method of manufacturing the wire grid polarizer, and a liquid crystal projector provided with the polarizer.
2. Description of the Related Art
Polarizers used in liquid crystal displays are generally classified as those composed of organic materials and those composed of inorganic materials (refer to the document “MD rear projection TV Technology Trend,” pp.7-8 [online], written by Tadashi Matsuo of Polatechno Co., Ltd., Internet <URL:http://www.polatechno.co.jp/contents/tech/public/pdf/0006/MDRPTV.pdf>). In particular, in the recent front or rear projection televisions intended for high luminance, optical elements composed of inorganic materials, such as wire grids, are increasingly used to improve the durability of optical components as the entire optical block becomes smaller due to the miniaturization of liquid crystal panels.
The polarizers composed of organic materials can be fabricated by stretching a film with the organic material coated thereon. On the other hand, the wire grids formed by inorganic materials necessitate the formation of a metal layer on a substrate such as glass, and patterning process using micro-fabrication technique. In particular, to obtain a desired characteristic in the visible light region, it is necessary to form a minute pattern in the submicron range. As shown in FIG. 11, such a minute wire grid is fabricated in a first method including the step of forming a metal layer composed of aluminum (Al) or the like on a glass substrate 101, and the step of forming minute linear projections 102A by patterning the metal layer with lithography method (for example, refer to U.S. Pat. No. 6,122,103).
Recently, several other manufacturing methods have also been proposed. That is, a second method employs lithography method and lift-off method using electron beam and X-rays (refer to Japanese Unexamined Patent Application Publication No. 10-153760). A third method includes the step of forming a metal film on a flexible dielectric substrate, and stretching the substrate and the metal film at a temperature equal to or below the melting point of the metal film (refer to Japanese Unexamined Patent Application Publication No. 2001-74935). A fourth method includes the step of transferring a minute pattern onto a hydrophobic thin film and a hydrophilic thin film by using nanoimprint lithography technology, and growing thin metallic wires by plating method (refer to Japanese Unexamined Patent Application Publication No. 2005-70456). A fifth method is a mass production method including the step of patterning a polymer film formed on a substrate by using embossing technique, and the step of forming a metal layer thereon and thereafter removing the polymer film, thereby obtaining a patterned metal structure (refer to Japanese Unexamined Patent Application Publication No. 2006-84776).